This invention relates to an antenna for a submarine.
The invention applies generally to the naval (or nautical) sector and, more specifically, to the production of military submarines.
The submarine is a watercraft capable of surface navigation and which, when necessary, can submerge for more or less extended periods of time to continue navigating underwater.
In this invention, the term “submarine” is used to mean any submersible watercraft, including naval vessels designed mainly for independent operation below the surface of the water and also able to navigate partly above surface.
In other words these naval vessels developed out of traditional “submersible” watercraft and thus fall within the scope of the invention.
During underwater operation, submarines often need to raise one or more antennas (in particular, the high-frequency antenna) above the surface of the water in order to be able to communicate with the outside.
Disadvantageously, the high-frequency antenna is often longer than the submarine sail it is housed in during underwater navigation, which leads to problems connected with its movement and housing because its size is such that it cannot be made as a single component.
To overcome this problem, the prior art teaches the use of an antenna equipped with a stylus (for communication) which is connected to a base member of the antenna by a flexible strap.
More precisely, the base member is made up of two antenna portions connected in series. The bottom portion is equipped with an insulating element and is connected to the tuner of the antenna.
In the prior art forms, the stylus is juxtaposed with the base member and the flexible strap is curved over (to form a sort of parabolic antenna) to connect the top of the base member to the bottom end of the stylus. Thanks to its flexibility, the strap keeps the two parts of the antenna (stylus and base member) connected, even during the vertical movement of the stylus, that is, while the stylus is being extracted.
The antenna (high frequency) thus obtained is of optimum length (approximately 7 metres) thanks to the combination of the different modular components, that is, the stylus, the strap and the base member.
It should be noted that all of the above is housed in a containment and lifting cylinder (for example a mast) located inside the submarine sail and is movable between a first, retracted position and a second, extended position, where the stylus slides vertically relative to the base member, thereby bending the strap.
Disadvantageously, this solution suffers from several drawbacks, connected with the poor insulation of the radiating element as a whole due to the need to use a large number of components which must in turn be perfectly insulated from each other.